JP2827919B2 - Semiconductor laser device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device having a window structure at an end face and capable of high light output operation and a method of manufacturing the same.

[0002]

FIG. 9 is a view showing a semiconductor laser device having a window structure at an end face portion. FIG. 9 (a) is a side view, and FIG. 9 (b) is a line IXb-IXb of FIG. 9 (a). FIG. In FIG. 9, 1 is an n-type GaAs substrate, and 2 is an n-type Al0.5 G formed on the n-type GaAs substrate 1.
a0.5 As lower cladding layer, 3 is a quantum well structure layer in which an AlGaAs well layer and an AlGaAs barrier layer are alternately formed on the lower cladding layer 2, and 4 is a p-type AlO layer formed on the quantum well structure layer 3. .5 Ga0.5 As upper cladding layer, 5 is a p-type G layer formed on the cladding layer 4.
aAs first contact layer, 6 is a region where silicon ions are selectively implanted into the end portions of lower cladding layer 2, quantum well structure layer 3, upper cladding layer 4, and first contact layer 5, and 7 is quantum well structure layer. 8 is a region disordered by silicon (window structure region), 8 is an n-type GaAs current blocking layer, 9
Is a p-type GaAs second contact layer, 10 is a p-side electrode, 1
1 is an n-side electrode.

Next, referring to FIGS. 10 and 11, FIG.
A method for manufacturing the semiconductor laser shown in FIG. 10 and 11 are views showing a method of manufacturing the semiconductor laser shown in FIG. 9 in the order of steps.

[0004] First, as shown in FIG.
An n-type Al0.5Ga0.5 As lower cladding layer 2, a quantum well structure layer 3, a p-type Al0.5Ga on an aAs substrate 1.
Each layer of the 0.5 As upper cladding layer 4 and the p-type GaAs first contact layer 5 is sequentially formed by an epitaxial method. The quantum well structure layer 3 is made of GaAs or AlGa.
An As well layer (not shown) and an AlGaAs barrier layer (not shown) are formed by alternately growing crystals.

[0005] Next, as shown in FIG.
The photoresist 12 is entirely formed on the aAs first contact layer.
Is applied, and an opening portion 13 of a photoresist 12 is formed in a portion where a window region is formed by a photolithography technique. The size of the opening 13 is suitably 40 μm □. Next, ion implantation is performed on the entire surface from above. Silicon is appropriate as an ionic species for disordering the quantum well structure layer 3.

Even if silicon is ion-implanted on the entire surface, silicon stops in the photoresist in a region covered with the photoresist 12, and thus is not implanted into the crystal. On the other hand, ions are implanted from the opening 13 into the crystal. As a result, an ion implantation region 6 is formed as shown in FIG. Note that disordering of the quantum well structure layer 3 does not occur only by implanting silicon ions.
Some heat treatment causes silicon atoms to diffuse in the crystal, causing disorder. As heat treatment, A
A method of annealing at 700 ° C. or higher while applying s pressure is generally used. When the heat treatment is performed, a region 7 disordered by silicon is formed in the quantum well structure layer as shown in FIG.

[0007] Next, as shown in FIG.
An insulating film 43 made of, for example, Si ₃ N ₄ or SiO ₂ is formed on the aAs first contact layer and patterned in a stripe shape. Using the patterned insulating film 43 as a ridge etching mask, a part of the p-type GaAs first contact layer 5 and a part of the p-type Al0.5 Ga0.5 As upper cladding layer 4 are removed by etching to form the ridge region 14. I do. As an etchant used for this etching, there is a mixed solution of tartaric acid and hydrogen peroxide, or a mixed solution of sulfuric acid, hydrogen peroxide and water.

Next, as shown in FIG. 11B, an n-type GaAs current block layer 14 is formed around the ridge region 14, and the ridge region 14 is buried. At this time, the insulating film 43 serves as a mask during crystal growth, and does not grow on the insulating film 43.

Next, after the insulating film 43 is removed by wet etching or dry etching, p-type Ga is removed.
A p-type GaAs second contact layer 9 is crystal-grown on the As first contact layer 5 and the n-type GaAs current blocking layer 14, and a P-side electrode 10 is formed on the second contact layer 9 by an n-type GaAs.
By forming the n-side electrodes 11 on the s-semiconductor substrate 1 respectively, a semiconductor device having a window structure as shown in FIG.

Next, the operation of the semiconductor laser having the window structure described above will be described. P-side electrode 10 is set to +,
When a voltage is applied so that the n-side electrode 11 becomes negative, the holes become the p-type GaAs second contact layer 9 and the p-type GaAs first contact layer 9.
The electrons are injected into the quantum well structure layer 3 through the contact layer 5, the p-type Al0.5 Ga0.5 As upper cladding layer 4, and electrons are injected into the n-type GaAs semiconductor substrate 1, the n-type Al0.5 G
a0.5 Quantum well structure layer 3 through As lower cladding layer 2
, And recombination of electrons and holes occurs, and stimulated emission light is generated in the quantum well layer. Then, if the amount of injected carriers is sufficiently increased to generate light exceeding the loss of the waveguide, laser oscillation occurs.

Next, the ridge structure will be described. In the ridge structure, n other than the stripe-shaped ridge region 14 is used.
In the region where the n-type GaAs current block layer 8 exists, the n-type GaAs current block layer 8 and the p-type Al0.5 Ga0.
No current flows because the nP junction composed of the 5As upper cladding layer is reverse biased. Therefore, since the current flows only through the ridge region 14, the current is concentrated only in the region of the quantum well structure layer 3 close to the ridge, and the current density reaches a sufficient current for laser oscillation. The n-type GaAs current blocking layer 8 has a property of absorbing laser light emitted from the quantum well structure layer 3. This is because the band gap energy of GaAs is set to be smaller than the effective band gap energy of the quantum well structure layer 3.
For this reason, since the laser light is strongly absorbed on both sides of the ridge region 14, the laser light is concentrated only in the vicinity of the ridge region 14, and the horizontal and transverse modes which are important in the operation characteristics of the semiconductor laser are stably monomodal. It becomes the shape of.

Next, the window structure will be described. In general, the maximum light output of an AlGaAs-based semiconductor laser that emits laser light having a wavelength in the 0.8 μm band used as a light source for an optical disk device such as a compact disk (CD) is determined by the light output at which end face destruction occurs. The end face destruction occurs because the crystal itself constituting the semiconductor laser is melted by the heat generated by the laser beam due to the light absorption of the surface state in the end face region, and the function of the resonator is no longer achieved. Therefore, in order to realize a high light output operation, it is necessary to devise a method that does not cause end face destruction even at a higher light output. For this purpose, a structure that makes it difficult to absorb laser light in the end face region, that is, a window structure that is “transparent” to laser light is effective.
The window structure 7 has a higher band gap energy than the quantum well structure layer 3 that emits laser light. The window structure 7 of the semiconductor laser described above is formed utilizing disorder of the quantum well structure layer 3 by Si ion implantation and subsequent diffusion of Si by heat treatment.

FIG. 12A shows the profile of the aluminum composition ratio of the quantum well structure layer 3 before disordering, as shown in FIG.
(B) shows the profile of the aluminum composition ratio of the quantum well structure layer 3 after disordering, respectively. FIG.
In (a), 50 is the aluminum composition ratio Al ₂ of the well layer, 5
1 denotes a Al composition ratio Al ₁ of the barrier layer. The thickness of the well layer is usually 20 nm or less. When an impurity such as silicon (Si) or zinc (Zn) is diffused into the quantum well structure layer 3, atoms forming the well layer and the barrier layer are mixed. As a result, the effective band gap energy of the quantum well structure layer 3 has a value substantially equal to that of the barrier layer (the Al composition ratio is Al ₃ ) as shown in FIG. Therefore, the bandgap energy of the quantum well structure layer 3 and the window region 7 disordered by the implantation and diffusion of silicon becomes larger than the effective bandgap energy of the quantum well structure layer 3, so that " It has a “transparent” window structure.

[0014]

In the semiconductor laser having the window structure described above, when Si is ion-implanted into the quantum well structure layer 3, the distance from the wafer surface to the quantum well structure layer 3 is about 1.7 μm or more. I have. This is the p-type Ga
This is because the thickness of the As first contact layer 5 needs to be 0.2 μm or more, and the thickness of the p-type Al0.5 Ga0.5 As upper cladding layer 4 needs to be 1.5 μm or more. In particular, p-type Al
Regarding the layer thickness of the 0.5 Ga0.5 As upper cladding layer 4, it is important to satisfy the above-mentioned layer thickness requirement in order to achieve the function of confining the laser light emitted from the quantum well structure layer 3. is there.

When attempting to implant Si ions at a distance of 1.7 μm or more, the acceleration voltage at the time of implantation must be 2 MeV or more. The Si atoms accelerated by the voltage lose energy while colliding with atoms in the crystal, and finally stop. At a high accelerating voltage exceeding 1 MeV, individual Si atoms have high energy, so that a large number of defects are generated in the crystal by Si ion implantation. Although such crystal defects are recovered to some extent during the subsequent annealing,
Numerous defects remain without complete recovery. Therefore, even if an attempt is made to increase the band gap energy by disordering the quantum well structure layer by ion implantation and diffusion of Si to form a window structure transparent to laser light, crystal defects are absorbed by laser light, so that the window structure is not absorbed. There is a problem that it will not work. In addition, when there are many crystal defects, the Si atoms themselves are trapped by the crystal defects and are difficult to diffuse, which causes a problem that disorder is less likely to occur. SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor laser and a method for manufacturing the same that have solved the above problems.

[0016]

According to the present invention, there is provided a semiconductor laser device comprising: a semiconductor substrate of a first conductivity type;
A lower cladding layer of a first conductivity type disposed on a plate,
The barrier layer and the well layer are alternately stacked on the cladding layer.
An active layer having a quantum well structure and a layer arranged on the active layer.
The first upper cladding layer of the second conductivity type provided and the laser resonance
Surface of the first upper cladding layer including the active layer near the end face of the container
Impurities were implanted into the stack on the semiconductor substrate side from
The first upper layer is applied to the disordered region and the active layer in the disordered region.
Disposed on the surface of the first upper cladding layer facing through the lad layer
Including the second upper clad layer of the second conductivity type
And a striped ridge extending in the longitudinal direction of the shaker .

In addition, around the ridge on the first upper cladding layer
Current block of the first conductivity type disposed so as to embed
It further comprises a layer .

Further , implantation is performed to form a disordered region.
The impurity is Si .

Further, according to the method of manufacturing a semiconductor laser device of the present invention, the first conductive type semiconductor substrate is formed on the first conductive type semiconductor substrate.
The lower cladding layer, barrier layer and well layer are alternately laminated.
Active layer having a quantum well structure and a first upper layer of a second conductivity type.
A first step of sequentially forming a lad layer and a first upper cladding.
On the surface of the semiconductor layer
Forming an ion implantation mask pattern having an opening in
Step 2 and using the ion implantation mask pattern as a mask
Impurity is ion-implanted and the active layer near the cavity facet is removed.
The third step of ordering and the ion implantation mask pattern
A fourth step of removing, and after the fourth step, a first upper crack.
Forming a second upper cladding layer of the second conductivity type on the surface of the
Fifth step, and disorder on the surface of the second upper cladding layer.
Opposing active layer via the first and second upper cladding layers
Stripe ridge extending in the longitudinal direction of the cavity
A sixth step of forming a mask pattern and the ridge mask
Having a second upper cladding layer using a mask pattern as a mask
And a seventh step of forming a ridge .

After the seventh step, the first upper clad is formed.
Fill the periphery of the ridge on the layer with a current block layer of the first conductivity type
It further includes a step of embedding .

Further , implantation is performed to form a disordered region.
The impurity to be formed is Si .

In the second step, GaAs of the second conductivity type is used.
s etching stopper layer and AlGaAs ion implantation
A step of sequentially forming a mask layer;
An insulator film is formed on the input mask layer, and a semiconductive film is formed on the insulator film.
Forming an opening in a predetermined region of a cavity end face of a laser diode
And AlGaAs ion injection using this insulator film as a mask.
Selectively etching the input mask layer,
The fourth step is to etch the insulator film formed in the above step.
, And then the AlGaAs formed in the above step.
The method includes a step of removing the s ion implantation mask layer .

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

In the semiconductor laser device according to the present invention,
A first upper cladding layer disposed on the active layer;
Surface of the first upper cladding layer including the active layer near the end face of the container
Impurities were implanted into the stack on the semiconductor substrate side from
A disordered region, disposed on the surface of the first upper cladding layer;
Since it has a ridge including the second upper cladding layer,
Thickness of upper cladding layer required to confine laser light
While forming the disordered region as a window structure
Energy required for impurity implantation can be reduced,
Reduces defects in the crystal and enhances the function as a window structure
It is possible that.

Further , around the ridge on the first upper cladding layer
Current block of the first conductivity type disposed so as to embed
Buried semiconductor laser
In the laser device, necessary to confine laser light
While ensuring the thickness of the upper cladding layer, the irregularity of the window structure
Energy required for impurity implantation in the formation of ordered regions
Lowering the defect density in the crystal
Function can be enhanced .

Further , implantation is performed to form a disordered region.
Since the doped impurity is Si, light in the disordered region
Low absorption.

Further, according to the semiconductor laser device of the present invention,
The manufacturing method is such that a semiconductor laser is formed on the surface of the first upper cladding layer.
Ion implantation mask having an opening in a predetermined region of the cavity end face
A mask pattern is formed and this ion implantation mask pattern
Ion implantation using the mask as a mask, and near the cavity end face.
Disorder the active layer next to it and use an ion implantation mask pattern
After removal, the second conductive type is formed on the surface of the first upper cladding layer.
Since the second upper cladding layer is formed, light confinement of laser light is performed.
Window while ensuring the thickness of the upper cladding layer necessary for
Impurity injection in forming disordered regions as structures
Energy required for crystal growth, resulting in defects in the crystal
Can be reduced .

After the seventh step, the first upper clad is formed.
Fill the periphery of the ridge on the layer with a current block layer of the first conductivity type
Embedded process, so that the embedded semiconductor
The formation of disordered regions as window structures in body laser devices
Upper cladding layer necessary to confine laser light
Energy required for impurity implantation while ensuring the thickness of
And defects generated in the crystal can be reduced .

Further , implantation is performed to form a disordered region.
Since the impurity to be doped is Si, light in the disordered region
A semiconductor laser device with low absorption can be formed .

In the second step, GaAs of the second conductivity type is used.
s etching stopper layer and AlGaAs ion implantation
A step of sequentially forming a mask layer;
An insulator film is formed on the input mask layer, and a semiconductive film is formed on the insulator film.
Forming an opening in a predetermined region of a cavity end face of a laser diode
And AlGaAs ion injection using this insulator film as a mask.
Selectively etching the input mask layer,
The fourth step is to etch the insulator film formed in the above step.
, And then the AlGaAs formed in the above step.
including a step of removing the s ion implantation mask layer.
Use photoresist as an ion implantation mask.
Contamination of the wafer due to photoresist,
Contamination of the wafer surface due to the resist stripper during removal of
No etching occurs.

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

【Example】

Embodiment 1 FIG. FIG. 1 is a view showing an embodiment of the present invention. FIG. 1A is a perspective view, and FIG.
It is sectional drawing in the b-Ib line. In FIG. 1, 1 is an n-type GaAs substrate, 2 is an n-type Al0.5 Ga0.5 As lower clad layer formed on the n-type GaAs substrate 1, and 3 is an AlGaAs well layer (shown in FIG. Z)
And a quantum well structure layer 15 in which AlGaAs barrier layers (not shown) are alternately formed. Reference numeral 15 denotes a p-type AlO.5 layer formed on the quantum well structure layer 3 and having a thickness of 0.05 to 0.5 μm.
5 Ga0.5 As first upper cladding layer 16 has a thickness of 1.0 to 1.45 μm formed on the first upper cladding layer.
The above p-type Al0.5 Ga0.5 As second upper cladding layer 5 is a p-type GaAs formed on the second upper cladding layer.
s The first contact layer, wherein the second upper cladding layer 16 and the first contact layer 5 constitute a ridge region 17. 1
Reference numeral 8 denotes a region in which silicon ions are selectively implanted into ends of the cladding layer 2, the quantum well structure layer 3, and the first upper cladding layer 15, and 7 denotes a disordered region (window structure region) in the quantum well structure layer. ) And 8 are n-type GaAs current blocking layers formed so as to bury the ridge region 17, and 9 is p-type Ga
The As second contact layer 10 is a P-side electrode, and 11 is an n-side electrode.

Next, a method of manufacturing a semiconductor laser device according to one embodiment of the present invention will be described with reference to FIGS.

First, as shown in FIG.
An n-type Al0.5 Ga0.5 As lower cladding layer 2, a quantum well structure layer 3, and a p-type Al0.5 G
a0.5 As Each layer of the first upper cladding layer 15 is sequentially formed by an epitaxial method. The quantum well structure layer 3
Is a GaAs or AlGaAs well layer and an AlGaAs
The s barrier layers are formed by alternately growing crystals. p-type Al
The layer thickness of the 0.5 Ga0.5 As first upper cladding layer is 0.5.
It is formed to have a thickness of 0.5 to 0.5 μm.

Next, as shown in FIG.
A photoresist 12 is applied on the entire surface of the 0.5 Ga0.5 As first upper cladding layer 15, and an opening 13 of the photoresist 12 is formed in a portion where a window region is formed by a photolithography technique. The size of the opening 13 is suitably 40 μm □. FIG. 2C is a view of the wafer as viewed from above, and the portions surrounded by broken lines in FIG. 2C indicate portions that become individual semiconductor laser elements. Next, ion implantation is performed on the wafer. Si is suitable as the ionic species that causes disorder. In this case, the distance from the wafer surface to the quantum well structure layer 3 is equal to the thickness of the first upper cladding layer. As described above, in this embodiment, the p-type Al0.5 Ga0.5 As Since the layer thickness is 0.05 to 0.5 μm, the accelerating voltage at the time of ion implantation may be about 60 to 600 keV, and the accelerating voltage may be reduced to 1/3 or less as compared with that described above. it can. For this reason, the defects generated in the crystal are also significantly reduced as compared with the case where the acceleration voltage of 2 MeV described above is applied.

Even if Si is ion-implanted from the upper surface of the wafer to the entire surface, the Si is stopped in the photoresist in the region covered with the photoresist 12, so that the ion is not implanted into the crystal. The disordering of the quantum well structure layer 3 does not occur only by implanting Si ions. Disordering occurs by diffusing Si atoms into the crystal by some heat treatment after ion implantation. As the heat treatment, annealing is performed at 700 ° C. or more while applying As pressure. As a result, FIG.
As shown in (a), a Si ion implantation region 18 and a quantum well structure layer (window structure) 7 disordered by Si ions are formed.

Next, as shown in FIG. 3B, a p-type Al0.5 Ga0.5 As second
Upper cladding layer and p-type GaAs first contact layer 5
Are sequentially epitaxially grown. Quantum well structure layer 3
Sum of the thicknesses of the p-type Al0.5 Ga0.5 As first upper cladding layer and the p-type Al0.5 Ga0.5 As second upper cladding layer in order to perform the function of confining the laser light emitted in step 1. Is required to be 1.5 μm or more. However, as described above, the p-type Al0.5 Ga0.5 As first upper cladding layer is formed to have a thickness of 0.05 to 0.5 μm. The layer thickness of the 5 Ga0.5 As second upper cladding layer needs to be 1 to 1.45 μm or more. Next, an insulating film ridge mask 19 formed by forming an insulating film on the entire surface of the wafer and patterning it in a stripe shape is formed as shown in FIG. 3B.

Next, as shown in FIG. 3C, using the insulating film ridge mask as a ridge etching mask,
-Type GaAs first contact layer 5 and p-type Al0.5
The ridge region 17 is formed by etching the Ga0.5 As second upper cladding layer 16. The ridge etching for forming the ridge region 17 is performed by p-type Al0.5Ga.
The etching may be performed halfway through the 0.5 As second upper cladding layer 16 or halfway through the p-type Al0.5 Ga0.5 As first upper cladding layer 15. An etchant used for the ridge etching includes a mixed solution of tartaric acid and hydrogen peroxide or a mixed solution of sulfuric acid, hydrogen peroxide and water.

Next, as shown in FIG. 3D, the n-type GaAs current blocking layer 8 is buried so as to fill the ridge region 17.
To form

Next, as shown in FIG. 3E, after the insulating film ridge mask 19 is removed by wet etching or dry etching, the insulating film ridge mask 19 is further removed on the p-type GaAs first contact layer 5 and the n-type GaAs current blocking layer 8. Then, a p-type GaAs second contact layer 9 is crystal-grown, and then an n-electrode 11 is formed on the n-type GaAs substrate 1 side and a P-electrode 10 is formed on the p-type GaAs second contact layer 9 side.

In this embodiment, as described above, the distance from the surface to the quantum well structure layer at the time of ion implantation is 0.05 to 0.5 μm, which is the layer thickness of the p-type first upper cladding layer. Ions can be implanted at an acceleration voltage, and defects are less likely to occur in the crystal. For this reason, the problem that crystal defects absorb laser light and stop functioning as a window structure, or the problem that if there are many crystal defects, Si atoms themselves are trapped by the defects and are difficult to diffuse and disorder is unlikely to occur. Therefore, the semiconductor laser having the window structure has good characteristics such as a high light output operation inherent in a semiconductor laser and a high reliability due to a high end surface breakdown level.

Embodiment 2 FIG. In the method of manufacturing the semiconductor laser according to the first embodiment, the outermost layer of the wafer after the first crystal growth is the p-type Al0.5 Ga0.5 As first upper cladding layer 15 (see FIG. )), This p-type A
A layer containing a large amount of Al, such as the 10.5 Ga0.5 As first upper cladding layer 15, is easily oxidized. If a layer containing Al is further formed on the oxidized layer, the crystallinity on the surface oxide film becomes extremely poor, which affects the reliability of the semiconductor laser. As a solution, before the second crystal growth,
That is, before the crystal growth of the p-type Al0.5 Ga0.5 As second upper cladding layer 16, a chlorine gas is flowed into the crystal growth furnace to oxidize the surface of the p-type Al0.5 Ga0.5 As first upper cladding layer 15. Try to remove the film.

Embodiment 3 FIG. As a solution to the oxidation of the surface of the p-type Al0.5 Ga0.5 As first upper clad layer 15 which is the outermost layer of the wafer after the first crystal growth, a method of removing the surface oxide film with chlorine gas has been described. If the time from the first crystal growth to the second crystal growth is long, the formation of the surface oxide film progresses, so that the surface oxide film may no longer be removed with chlorine gas. At this time, as shown in FIG. 4, during the first crystal growth, p
A GaAs surface protective layer 20 is formed on the first Al0.5 Ga0.5 As first upper cladding layer, and immediately before the second crystal growth, that is, p-type Al0.5 Ga0.5
By removing only the GaAs surface protective layer 20 by etching immediately before the growth of the As second upper cladding layer 16, the second crystal growth can be performed on a clean wafer surface. If the GaAs surface protective layer 20 is removed by etching and then etching is performed by flowing chlorine gas into the crystal growth furnace, the second crystal growth can be performed on a further clean wafer surface.

Embodiment 4 FIG. In the method of manufacturing the semiconductor laser according to the first embodiment described above, the ridge etching for forming the ridge region 17 does not necessarily stop selectively, and therefore must be controlled by the etching time. However, when the in-plane distribution of the epitaxial layer varies in a large area wafer, the p-type Al0.5 Ga
The portions of the 0.5 As first or second cladding layers 15 and 16 that remain without being etched may vary greatly within the wafer surface, which is a major cause of in-plane variations in semiconductor laser characteristics. Therefore, as shown in FIG. 5A, during the first crystal growth, p-type Al0.5 Ga
0.5 As p-type Al0.7 on the first upper cladding layer 15
A Ga0.3 As etching stopper layer 21 and a GaAs surface protection layer 20 are formed, and the ridge etching is performed by a mixed solution of an organic acid and hydrogen peroxide using the insulating film ridge mask 19 as a mask through the same steps as described above. When the etching is performed, the etching is stopped at the etching stopper layer 21, so that a uniform ridge shape can be obtained in the wafer surface as shown in FIG.

Embodiment 5 FIG. In a 0.78 μm-band semiconductor laser having the quantum well structure layer 3 made of an AlGaAs-based material, in order to prevent laser light from being re-absorbed by the etching stopper layer, Alt Ga1 having an Al composition ratio t of 0.2 or more is used. -T As must be used. on the other hand,
0.98 used as a light source for fiber amplifier excitation
In the μm band semiconductor laser, the well of the quantum well structure layer 3 has I
nGaAs is used. In this case, even if the etching stopper layer is made of GaAs, there is no fear of absorbing the laser beam. Therefore, the GaAs surface protective layer 20 shown in FIG. 4 can be used as it is as an etching stopper layer. However, since the GaAs surface protective layer remains as a component of the P-side semiconductor laser, it is necessary to dope the GaAs surface protective layer with a p-type impurity. At the time of ridge etching, first, p-type Ga
Only the As first contact layer 5 is selectively etched. In this case, a mixed solution of ammonia and hydrogen peroxide or a mixed solution of organic acid and hydrogen peroxide is used as an etching solution. Next, in the second etching, p-type Al0.5 Ga
Only the 0.5 As second upper cladding layer 16 is selectively etched so that the etching stops at the p-type GaAs surface protective layer 20. As an etchant for such selective etching, there is a chlorine-based etchant or a hydrofluoric acid-based etchant. In this embodiment, the ridge etching is stopped at the p-type GaAs surface protection layer 20, so that the ridge shape is formed with good uniformity on the wafer surface.

Embodiment 6 FIG. In the above-described embodiments, the photoresist 12 is used as a mask for ion implantation. However, contamination of the wafer surface by the photoresist itself, or contamination of the crystal surface by a resist stripping solution at the time of removing the photoresist, etching, and the like are used. By occurrence
Deterioration of crystallinity during crystal growth in the next step, p
Type Al0.5 Ga0.5 As First Upper Cladding Layer 15
May be etched by a resist stripping solution and may not have a predetermined film thickness. As a method of solving this, there is a method of using the epitaxial layer as an ion implantation mask as shown in FIG. As shown in FIG. 6A, an AlG layer is formed on the p-type GaAs etching stopper layer 20.
An aAs ion implantation mask layer 22 is formed, a patterning insulating film 23 is formed thereon, an opening is provided in a window region, and the patterned insulating film 23 is used as a mask.
The lGaAs ion implantation mask layer 22 is selectively etched. In order to perform this selective etching, the Al composition ratio of the mask layer 22 should be p-type Al0.5 Ga0.5 As.
The same composition ratio as that of the first upper cladding layer 15 is advantageous. After selective etching of the mask layer, Si ions are implanted into the entire surface of the wafer to form ion implanted regions 18. Note that, in the region where the mask layer 22 exists, the Si ions remain in the mask layer 22. After the ion implantation, the insulating film 23 is removed with hydrofluoric acid, the mask layer 22 is further removed, and a semiconductor laser can be obtained by the method described above. In this embodiment, since a photoresist is not used, high-quality crystal growth can be performed without being affected by the residue of the resist during the second crystal growth.

Embodiment 7 FIG. In the method of manufacturing the semiconductor laser according to the first embodiment described above, the method in which only the window region is ion-implanted and disordered is described. However, only the stripe region where the ridge is to be formed is covered with the photoresist 24 as shown in FIG. When the quantum well structure layer 3 is disordered by ion-implanting the entire region not covered with the photoresist 24, in addition to the refractive index difference caused by the ridge in the ridge region,
Due to the difference between the refractive index of the effectively reduced refractive index of the disordered quantum well structure region 7 and the refractive index of the non-disordered quantum well structure layer 3, more effective horizontal light confinement can be realized. The threshold current and the operating current can be reduced.

Embodiment 8 FIG. In the above embodiment, a rectangular shape having a stripe region is described. However, as shown in FIG. 8, when the stripe region is formed in a flared shape and the ridge is formed in a shape corresponding to the flare shape, the laser beam spreads along the flare. Therefore, the light density at the end face is reduced. In addition to the window structure,
With this effect, a higher light output operation can be performed.

Embodiment 9 FIG. In the above, the current block layer 8 is made of GaAs, but the current block layer 8 is made of Alw Ga1-w As (w>) having a higher Al composition ratio than the p-type Alv Ga1-v As second upper cladding layer 16.
In the configuration of v), a real refractive index guide structure is formed from the loss guide, and the waveguide loss is reduced. Therefore, there is an effect that the threshold current and the operating current can be reduced.

[0060]

As described above, the semiconductor laser according to the present invention is provided.
A first upper cladding layer disposed on the active layer;
And a first upper portion near an end face of the laser cavity and including an active layer.
Impurities are injected from the cladding layer surface to the semiconductor substrate side stack
Disordered region and the surface of the first upper cladding layer
A ridge including a second upper cladding layer disposed thereon.
The laser beam confinement
Disorder as window structure while ensuring the thickness of the lad layer
Energy required for impurity implantation when forming regions
Function because it can be lowered and the defects that occur in the crystal are reduced.
Power and high reliability semiconductor laser with high window structure
There is an effect that the device can be used.

Further , around the ridge on the first upper cladding layer
Current block of the first conductivity type disposed so as to embed
Since it is further provided with a layer, light confinement of laser light
Window while ensuring the thickness of the upper cladding layer necessary for
Impurity injection in forming disordered regions as structures
Energy required for crystal growth, resulting in defects in the crystal
High output and high with a highly functional window structure
Can be a reliable embedded semiconductor laser device
effective.

Further , implantation is performed to form a disordered region.
Since the doped impurity is Si, light in the disordered region
Semiconductor laser device with less absorption, higher output and higher reliability
There is an effect that can be placed.

Further, in the semiconductor laser device according to the present invention,
The manufacturing method is such that a semiconductor laser is formed on the surface of the first upper cladding layer.
Ion implantation mask having an opening in a predetermined region of the cavity end face
A mask pattern is formed and this ion implantation mask pattern
Ion implantation using the mask as a mask, and near the cavity end face.
Disorder the active layer next to it and use an ion implantation mask pattern
After removal, the second conductive type is formed on the surface of the first upper cladding layer.
Since the second upper cladding layer is formed, light confinement of laser light is performed.
Window while ensuring the thickness of the upper cladding layer necessary for
Impurity injection in forming disordered regions as structures
Energy required for crystal growth, resulting in defects in the crystal
A highly functional window structure.
Easily manufacture high-power and high-reliability semiconductor laser devices
There is an effect that can be.

After the seventh step, the first upper cladding
Fill the periphery of the ridge on the layer with a current block layer of the first conductivity type
Since the method further includes an embedding step,
Ensure the thickness of the upper cladding layer necessary for confinement
The formation of disordered regions as window structures
Energy required for implantation can be reduced,
Window structure with high functionality
Buried semiconductor laser device with high output and high reliability
Can be easily manufactured.

Further , implantation is performed to form a disordered region.
Since the impurity to be doped is Si, light in the disordered region
Semiconductor laser device with less absorption, higher output and higher reliability
There is an effect that the device can be easily manufactured.

In the second step, GaAs of the second conductivity type is used.
s etching stopper layer and AlGaAs ion implantation
A step of sequentially forming a mask layer;
An insulator film is formed on the input mask layer, and a semiconductive film is formed on the insulator film.
Forming an opening in a predetermined region of a cavity end face of a laser diode
And AlGaAs ion injection using this insulator film as a mask.
Selectively etching the input mask layer,
The fourth step is to etch the insulator film formed in the above step.
, And then the AlGaAs formed in the above step.
including a step of removing the s ion implantation mask layer.
Use photoresist as an ion implantation mask.
Contamination of the wafer due to photoresist,
Contamination of the wafer surface due to the resist stripper during removal of
Since no etching occurs, during the second crystal growth
High quality crystal growth and higher reliability
Effect of easily manufacturing a new semiconductor laser device
There is.

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing method according to an embodiment of the present invention in the order of steps.

FIG. 3 is a diagram showing a manufacturing method according to an embodiment of the present invention in the order of steps.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing still another embodiment of the present invention.

FIG. 6 is a diagram showing still another embodiment of the present invention.

FIG. 7 is a diagram showing still another embodiment of the present invention.

FIG. 8 is a diagram showing still another embodiment of the present invention.

FIG. 9 illustrates a semiconductor laser having a window structure.

FIG. 10 is a diagram showing a method for manufacturing a semiconductor laser having a window structure.

FIG. 11 is a diagram showing a method for manufacturing a semiconductor laser having a window structure.

FIG. 12 is a diagram showing an Al composition ratio of a quantum well structure layer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Lower cladding layer 3 Quantum well structure layer 5 First contact layer 7 Window structure area 8 Current block layer 9 Second contact layer 10 P-side electrode 11 N-side electrode 12 Photoresist 13 Photoresist opening part 15 First Upper cladding layer 16 Second upper cladding layer 17 Ridge region 18 Impurity implantation region 19 Insulating film Ridge mask 20 Surface protection layer 21 Etching stopper layer 22 Ion implantation mask layer 23 Insulating film

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-208388 (JP, A) JP-A-2-154492 (JP, A) JP-A-7-249827 (JP, A) JP-A-7-208 221386 (JP, A) JP-A-6-29621 (JP, A) JP-A-1-132189 (JP, A) 1995 (Heisei 7) The 56th Autumn Meeting of the Japan Society of Applied Physics 3 Volume 29p- ZB-6 p. 1130 (58) Field surveyed (Int. Cl. ⁶ , DB name) H01S 3/18

Claims (7)

(57) [Claims] 1. A semiconductor substrate of a first conductivity type, a lower cladding layer of a first conductivity type disposed on the semiconductor substrate, and a barrier layer and a well layer disposed on the lower cladding layer alternately. An active layer having a quantum well structure formed by stacking, and a first upper clad of a second conductivity type disposed on the active layer
Layer and the above-mentioned first layer near the laser cavity end face and including the active layer.
1 Impurities from the surface of the upper cladding layer to the semiconductor substrate
The disordered region implanted and disposed and the active layer in the disordered region are interposed through the first upper cladding layer.
And the first upper cladding layer
A resonator including a second upper cladding layer of two conductivity type;
And a stripe-shaped ridge extending in the longitudinal direction of the semiconductor laser device. 2. The method according to claim 1, wherein the periphery of the ridge on the first upper cladding layer is buried.
The current blocking layer of the first conductivity type,
The semiconductor laser device according to claim 1, further comprising: 3. An implanted region to form a disordered region.
2. The semiconductor laser device according to claim 1, wherein said impurity is Si . 4. An active layer having a quantum well structure in which a lower cladding layer of the first conductivity type, a barrier layer and a well layer are alternately stacked on a semiconductor substrate of the first conductivity type, a first step of sequentially forming a first upper cladding layer, on the surface of the first upper cladding layer, the resonator end of the semiconductor laser
Ion implantation mask pattern having an opening in the expected surface area
A second step of forming, and the ion implantation mask pattern impurity ions are implanted as a mask, a third step of disordering the active layer of the resonator end face neighborhood, the removing the ion implantation mask pattern Step 4
And after the fourth step, a second layer is formed on the surface of the first upper cladding layer.
A fifth step of forming a conductive type second upper cladding layer; and forming a disordered active layer on the surface of the second upper cladding layer.
The length of the resonator opposed to the first and second upper cladding layers via the first and second upper cladding layers.
A sixth step of forming a stripe-shaped ridge mask pattern extending in longitudinal direction, the ridge mask pattern as a mask, the second upper
The method of manufacturing a semiconductor laser device comprising a seventh step of forming a ridge having a cladding layer. 5. The method according to claim 5, further comprising the step of :
Buried around the ridge with the first conductivity type current block layer
The method for manufacturing a semiconductor laser device according to claim 4, further comprising the step of : 6. An implanted region for forming a disordered region.
5. The method according to claim 4 , wherein the impurity is Si . 7. The method according to claim 7, wherein the second step is GaAs etching of the second conductivity type.
Pitching stopper layer and AlGaAs ion implantation mass
Forming an insulating layer on the AlGaAs ion implantation mask layer sequentially ;
Then, the insulator film is provided on a predetermined surface of the cavity facet of the semiconductor laser.
Forming an opening in the region, and using the insulator film as a mask to form an AlGaAs ion implantation mask.
And selectively etching the mask layer.
Step etches the insulator film formed in the above step
And then remove the AlGaAs layer formed in the above process.
Removing the on-implantation mask layer.
A method for manufacturing a semiconductor laser device according to claim 4 .